MS is an autoimmune disease in which the immune system attacks the central nervous system. It results in damage to nerve fibers, disrupting communication between the brain and the body. The disease has a wide range of symptoms that include tingling or numbness in the limbs, movement and speech difficulties, weakness, fatigue, chronic pain, vision loss, and depression.

The most common form of MS is relapsing-remitting MS (RRMS), which affects about 80% of people with the disease. It’s characterized by periods of mild or no symptoms interspersed with periods of more severe symptoms, called relapses. It can change into a progressive form where symptoms worsen over time without any symptom-free periods. RRMS can be treated with drugs that suppress the immune system and reduce inflammation. However, these drugs can cause serious side effects, are costly, and patients may become resistant to them over time.

One promising treatment for MS is HDIT/HCT (high-dose immunosuppressive therapy with autologous hematopoietic cell transplant). The goal of this therapy is to “reset” a person’s immune system so that it will stop attacking their central nervous system. The treatment involves first collecting a patient’s hematopoietic stem cells (HSCs)—precursor cells that develop into blood cells. High-dose chemotherapy and other drugs are then used to deplete the immune system and remove disease-causing cells. Finally, the participant is infused with his or her own HSCs, which develop into red and white blood cells and re-establish their immune system.

Researchers from several sites across the country have been monitoring 24 volunteers, ages 26 to 52, who underwent HDIT/HCT treatment for RRMS. The interim 3-year findings of this phase II clinical trial, called HALT-MS, were previously published. The 5-year results of the study, which was funded by NIH’s National Institute of Allergy and Infectious Diseases (NIAID), were published online on February 1, 2017, in Neurology.

The researchers found that 5 years after the procedure, 69% of the participants showed no signs of progression of disability, relapse of MS symptoms, or new brain lesions (viewed by MRI). Most importantly, participants didn't take any MS medications after receiving HDIT/HCT. Fifteen of the participants—more than half—had a decrease in an index of MS disability. Side effects included infections, which are commonly associated with the toxic nature of the HDIT/HCT procedure. Three participants had disease progression and died during the follow-up period. None of the deaths were related to the transplant procedure.

“These extended findings suggest that one-time treatment with HDIT/HCT may be substantially more effective than long-term treatment with the best available medications for people with a certain type of MS,” NIAID Director Dr. Anthony S. Fauci says. “These encouraging results support the development of a large, randomized trial to directly compare HDIT/HCT to standard of care for this often-debilitating disease.”